Download 4.1 Earth`s Formation

4.1 EARTH’S FORMATION
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DAHS
Mr. Sweet
OBJECTIVES
Explain how most scientists explain the
formation of our solar system.
 Describe Earth’s size and shape and the
arrangement of its layers.
 List three sources of Earth’s internal heat.
 Describe Earth’s magnetic field.
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NEBULAR HYPOTHESIS
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Most widely accepted
model for solar system
formation
4.6 billion years ago
Cloud of gas and dust
rotating in space
Shrank due to pull of
gravity, spinning faster
Material collected at
center and became hot.
Hydrogen fusion began
creating our sun.
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PLANETISMALS
Frictional, electromagnetic, and gravitational
forces formed solid particles of ice and rock.
 Eventually formed planets and moons.
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OBLATE SPHEROID
A sphere that bulges
in the center.
 Shape of Earth.
 Proof

Measuring the weight
of object at several
places on Earth.
 195 Newtons at Poles
and 194 Newtons at
equator.
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EARTH’S MEASUREMENTS

Total surface area
510 million square km
 55 continental USA’s

149 million square km
is above sea level
 Ocean covers 361
million square km
 29% dry, 71% wet
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ORIGINAL EARTH
Looked like the moon
 Same material all the
way thru
 Collisions created
heat
 Heat melted iron and
nickel
 Denser material
moved to the center
and lighter materials
to the surface
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LAYERS OF EARTH
Inner Core
 Outer Core
 Mantle

Lithosphere
 Asthenosphere
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Crust
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INNER CORE
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Solid iron and nickel
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OUTER CORE
Surrounds the inner
core
 Composed of liquid
iron and nickel
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MANTLE
Thickest of Earth’s
layers
 Iron, Silicon, and
magnesium
 Solid
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High pressure and
temperatures cause it
to behave as a liquid.
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CRUST
Thin, rigid layer
 Lighter rocks
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OTHERS
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Lithosphere
Crust and uppermost
mantle
 More rigid material
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Asthenosphere
Slushlike layer of
mantle
 Lithosphere floats on
top
 Cause of plate
tectonics
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EARTH’S HEAT
Meteorite impacts
 Compression of
Earth’s interior
 Decay of radioactive
isotopes
 Slowly losing heat


Differences in rock,
crust thickness, and
radioactive rock
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TEMPERATURE AT DEPTH
Above 70 feet
temperature remains
constant year round
 Below 70 feet
temperature rises 1o
Celcius every 40
meters
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MAGNETIC FIELD
North Pole is the
positive pole
 South Pole is the
negative pole
 Tilted 11O away from
the poles
 Hypothesized that the
fluid outer core
creates the magnetic
field
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
Iron moves through
and electric field
creating another
electric field
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SECTION REVIEW 4.1
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Page 74 Numbers 1, 2, 3, and 4
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